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Seminario: Delzant polytopes in the non-commutative case

Lunedì 15 Giugno 2015, ore 14:00 - Aula 2AB40 - Guido Pezzini

ARGOMENTI: Seminari

Lunedì 15 Giugno 2015 alle ore 14:00 in Aula 2AB40, Guido Pezzini (Erlangen-Nurnberg) terrà un seminario dal titolo "Delzant polytopes in the non-commutative case".

Abstract
A celebrated theorem of Delzant states that a multiplicity-free Hamiltonian action of an abelian compact Lie group K is uniquely determined by the associated moment polytope. Admissible polytopes are the well-known Delzant polytopes.
This uniqueness property, thanks to works of Losev and Knop, has been generalized to the case where K is non-abelian, but in this case the problem of describing the admissible polytopes is much more difficult.
It is also equivalent to characterizing combinatorially the weight monoids of smooth affine (complex) spherical varieties. In this talk we will describe a solution to this problem, and discuss some consequences on the moduli scheme of affine spherical
varieties.

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